The present invention relates to supports for pipelines and in one aspect relates to movable supports spaced along a pipeline wherein the supports are laid on the ground to elevate the pipeline so that water or small wildlife can readily pass thereunder but at the same time allow the pipeline to move freely in response to thermal expansion/contraction or pressure surges.
The concept of laying a flexible pipeline directly on the ground in a remote area (e.g. on tundra in arctic regions) is attractive in that it has several inherent advantages. First, the cost of trenching and burying the line or supporting the pipeline above the ground on xe2x80x9cpermanentxe2x80x9d pilings or supports is eliminated. Second, access to a pipeline lying directly on the ground is very easy since no digging or scaffolding is required when maintenance is required. Finally, the pipeline can be moved or removed much easier and at much less expense than a line that is buried or elevated on permanent pilings while, at the same time, causing much less damage to the existing environment.
Unfortunately, however, there are some disadvantages in laying a pipeline directly on the ground. For example, during rainy weather or a spring thaw, the pipeline functions as an artificial dam, creating a small xe2x80x9criverxe2x80x9d along the pipeline right of way which, in turn, can cause serious erosion problems. Also, due to the size of some pipelines, certain small animals may have trouble crossing the lines.
In order to provide ready access to a pipeline and at the same time allow water and small wildlife (e.g. molting birds, etc.) to readily pass under the pipeline, it has been proposed to support the pipeline on spaced, low-profile supports such as railroad ties or the like. However, this type of support is not free to move with the pipe if and when the pipe undergoes movement (e.g. temperature expansion/contraction, pressure surges, etc.) during operation. This rubbing of the pipe against the support can lead to serious damage to the surface (e.g. tundra) under the support as well as possible damage to the pipeline, itself. Further, xe2x80x9crailroad-tiexe2x80x9d types of support may be difficult to install in extremely remote or rugged terrain since they normally require a wide, flat area to be effective.
The present invention provides a pipeline for conveying fluids which is comprised of a length of pipe which is supported by a plurality of movable supports which, in turn, are positioned around said pipeline at spaced intervals along the pipeline. The supports are movable with respect to the surface of the earth (e.g. tundra) thereby allowing said pipeline to move in response to temperature/pressure changes in said pipe. The supports are sized so that the pipeline will be elevated above the surface of the tundra at a height sufficient to allow water to flow under the pipeline as well as allowing small animals to pass thereunder.
More specifically, the movable supports may be rolling supports or sliding supports or preferably a combination of both. A rolling support in accordance with the present invention is comprised of a cylindrical shell which has a central bore therethrough which, in turn, is adapted to receive the pipe. The diameter of the central bore is larger than the outside diameter of the pipe whereby the pipeline is free to move longitudinally within the cylindrical shell. Preferably, the cylindrical shell is comprised of two substantially identical halves (e.g. formed from a plastic material) which are adapted to be secured together after they have been positioned around the pipe. One half of the cylindrical shell is adapted to lie directly on the ground after it has been assembled onto the pipeline.
Each sliding supports of the present invention is comprised of a slidable stand which, in turn, is comprised a saucer-like, partial-spherical base which is adapted to be positioned in movable contact with said surface of the tundra. A plurality of vertical members are affixed to the base and extending upward therefrom. A cylindrical shell, similar to that of a rolling support is positioned on and supported on the vertical members whereby the cylindrical shell will move with said base. Again, the cylindrical shell is comprised of two substantially identical halves which have a central bore therethrough when assembled in which the pipeline is received. The diameter of said central bore is substantially equal to the outside diameter of the pipe whereby the pipeline will be clamped within said central bore when said halves of said cylindrical shell are assembled around said pipe. This tight fit prevents the pipe from moving longitudinally with respect to said cylindrical shell.
In constructing the pipeline, a plurality of the movable supports are spaced along the length of the line. Since the supports are not anchored to the surface, they are free to move in response to any pressure surges in the line or any expansion/contraction of the pipeline due to temperature changes. The rolling supports will xe2x80x9crollxe2x80x9d across the tundra while the sliding supports will xe2x80x9cslidexe2x80x9d and/or xe2x80x9crockxe2x80x9d in response to any significant changes in the pipeline thereby substantially elimination any possible damage to either the pipeline or the tundra.